You can certainly try it, but don't expect anything.  It's really a function
of how long the van sits.  Drive every day and you probably won't have the
problem, especially if you use 15w-40 or 20w-50 oil.  I currently run
20w-50, but my engine is the wear limit for oil pressure, and the knock
starts after about a week of sitting.

I think it's a problem with worn check valves in the lifter, but replacing
the lifters is expensive and potentially can create worse problems with cam
lobe wear on an old cam.  VW cam lobes do double duty, there are only four
lobes for 8 valves.

It's just one of those endearing features of the WBX engine we live with.

Stuart

-----Original Message-----
From: PSD [mailto:psdooley@verizon.net]
Sent: Friday, July 03, 2015 11:59 AM
To: 'Stuart MacMillan'; vanagon@GERRY.VANAGON.COM
Subject: RE: lifter chatter any concerns?

I have used ATF in other makes with decent success.  Maybe the difference is
a worn lifter as opposed to a clogged or stuck one?

-----Original Message-----
From: Stuart MacMillan [mailto:stuartmacm@gmail.com]
Sent: Friday, July 03, 2015 11:38 AM
To: 'PSD'; vanagon@GERRY.VANAGON.COM
Subject: RE: lifter chatter any concerns?

ATF and Marvel Mystery Oil both have solvent properties, but modern oils now
have high detergent capability to prevent sludge buildup.

I've tried MMO at the recommended 25% in both my '84 and '85 to no avail.
They also thin the oil. I wouldn't know how much ATF to use, but don't
bother with either of them.